Constructal design of weight optimized metal hydride storage device embedded with ribbed honeycomb

• Performance of metal hydride storage device embedded with constructal design of aluminum honeycomb is studied numerically. • Effect of salient geometric parameters on the weight optimized hydrogenation performance of the device is studied. Solid state storage of hydrogen offers few advantages over compressed and liquefied forms. As heat transfer being the major factor controlling charging and discharging, several thermal enhancement methods were reported in literature. However parasitic weight of thermal enhancement structures embedded to the storage bed can reduce its gravimetric storage capacity. As total weight of the device for given hydrogenation capacity and charging rate being an important factor, these structures needs to be weight optimized. The present study propose a ribbed honeycomb embedded to the multi-tubular storage device with sodium alanate as the storage alloy. The shape and size of this conform to the constructal law, analogous to bio transport systems. This ensures efficient transfer of sorption heat from the point of maximum temperature in the hydride bed to the coolant. The device designed for charging 0.01 kg of hydrogen in 10 min weighs 1.2 kg at optimum length/thickness ratio. This numerical study is conducted using COMSOL Multiphysics™ commercial code.